This study presents a comprehensive process, economic, environmental, and socioeconomic analysis of the enzymatic recycling of poly(ethylene terephthalate), which is the most widely used synthetic polyester. The analyses predict that PET deconstruction using enzymes can achieve cost parity with terephthalic acid manufacturing as well as substantial reductions in both supply chain energy use and greenhouse gas emissions relative to virgin polyester manufacturing. This study also highlights key research areas for further impactful development of biocatalysis-enabled plastics recycling.

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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. U.S. Department of Energy (DOE) reports produced after 1991 and a growing number of pre-1991 documents are available free via www.OSTI.gov.

The production of commodity organic chemicals today is both primarily sourced from and powered by fossil carbon resources. Toward decarbonization of this key global economic sector, it is imperative to quantitatively understand the contributions to energy usage and greenhouse gas (GHG) emissions along the petrochemical manufacturing supply chain, which can inform judicious policy development and impactful technology options to improve or reimagine existing manufacturing practices. To that end, here we use the Materials Flows through Industry (MFI) tool to estimate the supply chain energy and GHG emissions for 51 organic petrochemicals and 6 intermediates that are globally produced at a capacity of at least 1 million metric tons (MMT) per year. This analysis focuses on supply chains in the United States, from which industrial data are readily sourced to obtain accurate energy and GHG emission estimates. Analysis for each chemical includes contributions from sourcing chemical feedstocks, electricity use, and fuel usage for transportation and manufacturing. This analysis predicts that process fuel, which is primarily used for heating, dominates GHG emissions in all cases except for chlorochemicals, where electricity is used extensively for the chloroalkali process and results in a large electricity GHG emission contribution ranging from 7 to 54% of total GHG emissions. Additionally, the contribution of electricity to GHG emissions ranges from 6 to 63%, representing the decarbonization potential in the transition toward renewable electricity with existing manufacturing processes. Taken together, these data serve as a critical baseline toward industrial decarbonization of the organic chemical sector, against which to compare changes to the electrical grid and industrial heat sources, improvements to existing technologies to manufacture the same chemicals, and new technologies to source alternative feedstocks to manufacture direct or functional replacement chemicals.

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